1. Field of the Invention
The present invention relates to treated textile fabric and to a method of treating a textile fabric. The present invention more particularly relates to a method of preparing a water resistant, water repellant, and stain resistant fabric, and to the textile fabric so prepared.
2. Background Art
Stain resistance, water repellency and water resistance are important in many uses of textile materials. In restaurants, for example, table cloths and seating upholstery often lack stain resistance and are subject to rapid liquid, i.e., water, penetration. These properties necessitate frequent cleaning and/or replacement of such items. Although one generally views microbial growth as being associated with fibers of biologic origin such as cotton, wool, linen and silk, in the field of marine use, the high relative humidity renders even synthetic polymer textiles, such as polyesters and polyamides, subject to microbial growth, which is also true of many other outdoor uses.
The term “water resistant” as used herein means essentially impermeable to liquids, such as water, i.e. treated textile fabric can support a considerable column of water without water penetration through the textile fabric. Such behavior is sometimes incorrectly termed “water repellant.” However, the last term generally implies a lesser degree of water resistancy. Water repellency refers to the beading up and running off of water on a surface. Hydrophobicizing topical treatments are incapable of providing the necessary degree of water resistance as that term is used herein.
Textile fabrics may be made somewhat water repellant by various processes. For example, textile fabrics may first be scoured with a soap solution and then treated with a composition which may include zinc and calcium stearates as well as sodium soaps. The long chain carboxylic acid hydrophobic compounds provide a limited amount of water repellency. It is also possible to render fabrics somewhat liquid repellant by treating the fabric with commercially available silicone, for example poly(dimethylsiloxane).
To overcome problems associated with water absorption and stain resistance, resort has been made to synthetic leathers and polyvinylchloride (vinyl) coated fabrics. However, these fabrics do not have the hand or feel of cloth. Moreover, although attempts have been made to render such materials water vapor permeable, these attempts have met with only very limited success, as evidenced by the failure of synthetic leather to displace real leather in high quality seating and footwear.
Applications of relatively small amounts of fluorochemicals, such as the well known SCOTCHGUARD™ to textile fabrics and similar compounds, also may confer a limited degree of both water repellency and stain resistance to the textile fabric. However, these “SCOTCHGUARD™ed” textile fabrics are incapable of providing the degree of water repellency, water resistance, and stain resistance, as achieved by the present invention. Other methods of providing water repellant fabrics include coating the top surface of fabrics with thick polymeric coatings. These polymeric coatings, being on the top surface of the fabric, completely destroy the hand and feel of the fabric. Examples include vinyl boat covers, where the fabric backing is rendered water repellant by application of considerable quantities of polyvinylchloride latex or the thermoforming of a polyvinyl film onto the top of the fabric. The fabric no longer has the hand and feel of untreated fabric, but is plastic-like. Application of polyurethane films in the melt has also been practiced, with similar results. Moreover, unless aliphatic isocyanate-based polyurethanes are utilized, the coated fabric will rapidly weather.
The applicants of the present invention developed a treated fabric known as CRYPTON™ which is disclosed in U.S. Pat. Nos. 5,565,265 and 6,024,823. The Crypton™ fabric is liquid repellant, liquid resistant, stain resistant and antimicrobial. The Crypton™ fabric is prepared by topically treating a fabric with a first, relatively low viscosity, aqueous treatment composition comprising an antimicrobial agent and a substantial amount of fluorochemical treatment composition. After passing through the first bath, the fabric is dried and cured, and then a relatively high viscosity treatment composition is knife-coated on the backside of the fabric to further treat the fabric, which is then dried and cured again. This knife coat treatment can be done once, or more than once.
It would be desirable to provide a fabric that allows water vapor to pass through the fabric while prohibiting the passage of liquid. It would also be desirable to provide a method of producing a liquid repellant, liquid resistant, stain resistant fabric. It would further be desirable to provide a liquid repellant, liquid resistant, stain resistant fabric that retains its natural hand and texture, is easy to handle, and economical to produce. Moreover, it would be further desirable to provide a liquid repellant, liquid resistant, stain resistant fabric that can be made relatively cleanly and with relatively little expenditure of time and money.